1. Field of the Invention
The present invention relates generally to electromagnetically operated valves and more specifically to an electromagnetic valve suited to use in vacuum or fluid flow control systems and the like.
2. Description of the Prior Art
A prior art valve disclosed in JP-A-58-172166 includes a yoke on which an armature is pivotally mounted, a solenoid or similar type selectively energizable electromagnetic device, and a spring which biases and holds the armature at a predetermined angle with respect to the yoke when the electromagnetic device is not energized. The arrangement further includes a valve body which is supported on the armature by way of the springy member. However, this arrangement has suffered from the following problems. As the springy member is disposed between the valve body and the armature, in order to move the valve body from an open position to one wherein it engages the port which it is is designed to close, and then further press the valve body against the port of the valve arrangement to the point that the port is hermetically closed, a relatively large amount of movement or stroke of the armature is necessary. Viz., it is necessary to move the valve body to the point where it actually contacts the valve port and then move an additionally amount in order to compress the spring member to the point that the required pressure is applied and the valve port is hermetically sealed.
Further, when the electromagnetic device is de-energized a predetermined amount of movement or stroke of the armature is necessary in order to reduce the compression in the springy member before the valve body is actually permitted to move away from the valve port. Thus, due to the need to compress and de-compress the springy member before the valve is completely closed or begins to open respectively, the opening and closing response characteristics of the valve is poor and reduces the precision with which the supply of vacuum or the like can be controlled.
With this arrangement, as the valve body serves as the reaction member which, in combination with the springy member, stops the movement of the armature toward the valve port, valve body tends to be subject to excessive wear which reduces the working life of the same.